Lateral inner environment changes and effects on emitter clogging risk for different irrigation times

We characterize the variation in the inner lateral environment with five indexes. The emitter clogging risk was affected by the drip irrigation time. The emitter clogging risk was significantly correlated with sediment mass and particle size composition. Lateral flushing changes the adhesion direction of the clogging materials and lowers the emitter clogging risk. Emitter clogging is one of the most important limiting factors affecting the promotion of drip irrigation. To examine the impact of the irrigation time on the lateral environment and to develop an optimal way to mitigate the emitter clogging risk, 4 different irrigation times (3, 7, 10 and 30 times) were examined with each irrigation period lasting 2 daily hours. Then, the lateral inner environment was studied from the perspectives of the mass, particle size composition, mineral composition, microbial content of the sediment in the lateral (includes sediment deposited in and adhered to the lateral, DS and AS, respectively). The index of the emitter clogging risk was used to indicate the emitter clogging level of the drip irrigation system. The results indicated that emitter clogging risk (Rec) was significantly correlated with the DS mass, AS mass, rate of change of the AS mass and fractal dimension (p < 0.01), and the AS mass was correlated with the bacterial content in the AS (p < 0.05). This finding indicates that Rec was affected by the lateral inner environment. The DS affected the changes in Rec, mainly through influencing the mass of clogging substances in the grid structures and the particle size across the labyrinth channel. The increasing AS captures nutrients and provides a suitable environment for the growth of bacteria in the laterals, inlet grid and labyrinth channel. Additionally, the mass of clogging substances (mainly the AS) increased steadily during the process of particle adhesion, which leads to irreversible clogging. The Rec declined rapidly in the initial stage of irrigation and then gradually decreased over the irrigation duration. There was a boundary between short and long irrigation times (between irrigation times of approximately 7 and 10 in this research), which was the optimum lateral flushing period.